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Study of in-flight particle stream and particle behavior for understanding the instability phenomenon in plasma spraying process

Liu, Taikai and Arnold, Johannes (2016) Study of in-flight particle stream and particle behavior for understanding the instability phenomenon in plasma spraying process. Surface and Coatings Technology, 286C, pp. 80-94. Elsevier. DOI: 10.1016/j.surfcoat.2015.12.014 ISSN 0257-8972

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Official URL: http://www.sciencedirect.com/science/article/pii/S025789721530445X

Abstract

For understanding the effect of powder feeding fluctuation on coating structure, in-flight particles were investigated by means of image analyzing. Particle behavior was estimated through numerical calculation on the base of force equilibrium. High definition videos were captured focusing on the in-flight particle stream and transparent carrier tube. Yttria-stabilized Zirconia (YSZ) coating was prepared with vacuum plasma spraying for clarifying the effect of powder feeding instability on coating structure. Optic micro-morphology of coating was obtained for porosity ratio estimation. An imaginary ring of bent tube was proposed for understanding particle behavior when unavoidable bends exist. Results indicate that periodic fluctuations exist in in-flight particle trajectory and in powder feeding. A transition region was found for particles with different diameters in regions between 0° and 180° within which particles with large sizes are difficult to transport. As a consequence, accumulation of powder was thus found both on upslope and downslope. The effective cross-section of the carrier tube for powder carrying was found reduced. According to the calculation, reducing equivalent diameter and increasing carrier gas flowrate have the same effect on powder carrying. A threshold was proposed to understand the slug behavior as: growing, maturity and breaking. Due to the break of slug, ‘powder flooding’ happens and may cause mutation in in-flight particle stream. Obvious increase was found in injected particle quality to induce the three-layer structure of coating. An empirical equation was proposed to describe slug behavior as a synthesis of growth rate and loss rate.

Item URL in elib:https://elib.dlr.de/100647/
Document Type:Article
Additional Information:DLR/DAAD Research Fellowship Program for Post-docs
Title:Study of in-flight particle stream and particle behavior for understanding the instability phenomenon in plasma spraying process
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Liu, Taikaitaikai.liu (at) dlr.deUNSPECIFIED
Arnold, Johannesjohannes.arnold (at) dlr.deUNSPECIFIED
Date:January 2016
Journal or Publication Title:Surface and Coatings Technology
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:286C
DOI :10.1016/j.surfcoat.2015.12.014
Page Range:pp. 80-94
Publisher:Elsevier
ISSN:0257-8972
Status:Published
Keywords:Powder feeding instability; Plasma spraying process; Coating structure; Particle behavior; Slug description
HGF - Research field:Energy
HGF - Program:Storage and Cross-linked Infrastructures
HGF - Program Themes:Fuel cells
DLR - Research area:Energy
DLR - Program:E EV - Energy process technology
DLR - Research theme (Project):E - Electrochemical Processes (Fuel Cells) (old)
Location: Stuttgart
Institutes and Institutions:Institute of Engineering Thermodynamics > Electrochemical Energy Technology
Deposited By: Liu, Taikai
Deposited On:01 Dec 2017 15:02
Last Modified:31 Jul 2019 19:57

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